In vehicle building, great efforts have been made for decades to reduce the weight of vehicles. Great importance is attached in this respect above all to moving masses, more particularly the wheels. For a long time purchasers of motor vehicles have already had the option of choosing between a light aluminium wheel and a heavy steel wheel. Despite the advantage of an aluminium wheel in view of the improved driving behavior of the motor vehicle and the cheaper operating costs of a vehicle equipped with light metal wheels, predominantly steel wheels are purchased, as they are substantially more reasonable in price.
The majority of steel wheels used in practice are welded together from a ready-shaped rim and a ready-shaped wheel disc/dish. In such a wheel the wheel disc/dish can be made from a material of greater thickness than that of the wheel rim, however, the cost of manufacturing such a wheel is high due to the separate deformation of the wheel disc/dish and the wheel rim and the subsequent welding together of the two parts.
Light construction aluminium and steel wheels are also known which are produced from a flat circular disc by shaping and splitting (DE 34 10 308 A1, DE 32 39 675 C2) These vehicle wheels are made by the outer edge of the circular discs being split radially into two rings, which are opened up, the rim being formed therefrom. Such a wheel is therefore given its light construction by the most heavily loaded wheel disc/dish being made from a thicker material and the rim from a thinner material. Even though such a wheel is made from one piece, its cost is high, due to the opening up of the outer edge of the circular disc.
It is an object of the invention to provide a light construction wheel for vehicles whose production is as simple as possible.
This problem is solved according to the invention by a light construction wheel which is made by cold working from a circular steel sheet disc. The light construction wheel has a wheel disc/dish and a wheel rim, more particularly for tires, the wheel disc/dish being formed from a first flat circular disc and the wheel rim from a second flat circular disc welded thereto. The first and second circular discs are made from different sheets which differ in thickness and/or strength of material in accordance with the locally given strength requirements. The sheets can be uncoated or coated, for example given a surface finish.
Furthermore, an aluminium rim made from sheet metal is known for vehicles having pneumatic or rubber tires (EP 0 054 931 A2). The rim is produced by a start being made from a flat circular disc which in a first step is deformed pot-shaped. This already gives the lower zone of the wall a shape from which the two rim horns are formed after parting. After separation, the wall of the other side of the end is welded on and co-operates with the radially outer part of the end and the lower portion of the wall to form the rim dish. Such a process of production is expensive, due to the necessity of separating a portion of the shaped circular disc and the welding-on required.
Lastly, a disc wheel in the form of a welded sheet metal construction is known for a vehicle having pneumatic tires (DE 31 44 090), wherein the wheel disc thicker in material merges via its thinner edge, forming a rim horn, into the rim bed of thinner material. This prior art does not disclose from what sheet metal blanks a start is made for the wheel disc and the wheel rim.